[ns] Help, for snoop.tcl

[Kai Xu <xuk@eecs.umich.edu>]

Dear Sir,

Currently, we are working on a course project focusing on "snoop"
protocol, and we want to use NS to do some simulation experiments. But
when we run the snoop.tcl script, we got following problems. 

Firstly, when we run snoop.tcl we get following warning and errors,

ns snoop.tcl -e 0.2 -eu time -stop 10 -ll LLSnoop -r

warning: Warning: use `drop_tail_' rather than `drop-tail_'
invalid command name "Mac/Csma/Ca"
    while executing
"Mac/Csma/Ca create _o45 "
    invoked from within
"catch "$className create $o $args" msg"
    (procedure "new" line 3)
    invoked from within
        ....
        ....
"$ns make-lan $nodelist $opt(bw) $opt(delay)  LL $opt(ifq) $opt(mac)
$opt(chan)"
    (procedure "create-topology" line 17)
    invoked from within
"create-topology $opt(num)"
    (file "snoop.tcl" line 378)


Next, we change "Mac/Csma/Ca" with "Mac/802_11" in the script, but we got
following errors again,

warning: Warning: use `drop_tail_' rather than `drop-tail_'
can't read "lanIface_(1)": no such element in array
    while executing
"set nif $lanIface_([$dst id])"
    (procedure "add-error" line 4)
    invoked from within
"add-error $lan $src $dst $e1"
    (procedure "create-error" line 25)
    invoked from within
"create-error $lan $node(0) $dstlist $opt(em) $opt(e)  $opt(eu)
$opt(trans)"
    invoked from within
"if { [info exists opt(e)] } {
        if { $opt(e) == 0 || $opt(e) == "" } {
                puts "error rate 0 ==> no errors"
        } else {
                if { [info exists opt(www)] } {
..."
    (file "snoop.tcl" line 385)


Could you please tell us how to fix these errors? Now, we are using the
Release of ns-2.1b6. Shall we change to another older release to run this
script properly? Or a newer one (2.1b7)? Your kindly help and advice is
very important for us. Thanks.

Looking forward to your reply.

Best Regards,

Kai Xu

EECS dept.
U of Michigan.